Tissue oxygenation (StO2) is a proven indicator of perfusion status in patients experiencing undifferentiated shock. High-risk patients who receive continuous monitoring of StO2 from the trauma bay through ionizing radiation, such as X-ray and CT imaging, and other procedures to the operating room have been shown to receive effective interventions sooner, resulting in significant reductions in ICU admission, length of stay, morbidity and mortality.
Near infrared spectrometer systems are known and reported in, for example, U.S. Pat. No. 5,411,023 to Morris, Sr. et al. and U.S. Pat. No. 6,377,840 to Gritsenko et al. U.S. Pat. No. 5,411,023 discloses an optical sensor system for use on a patient in an MRI or other electrically isolated environment. Control and display modules transmit and receive electrical signals to a remotely located light source and light detector, respectively. Fiber optic cables transmit and receive analog optical signals between the light source/detector and the patient within the electrically isolated environment. Electrical signals from the light detector are transmitted over an electrical cable for analysis by the control unit to determine the patient's heart rate and oxygen saturation. To insure accurate analysis, the control unit is typically customized to work specifically with the remotely located light source and light detector. The fiber optic cables extend from the patient to outside the electrical field. In this way, attenuation of the analog optical and electrical signals is minimized. The fiber optic cables are susceptible to damage from exposure to radiation procedures such as X-ray and CT imaging. To prevent damage to the fiber optic cables, the patient interface is typically removed from the patient during radiation procedures.
U.S. Pat. No. 6,377,840 discloses a spectrophotometric instrument utilizing multiple LED's to provide measurement radiation at discreet wavelengths. The spectrometer includes an electronics package, a remotely located optical probe for interfacing with the patient measurement site and a probe connector for coupling the optical probe to the electronics package. The electronics package includes a processor/controller and an optical bench for detecting and processing radiation that has been reflected from the measurement site. The probe connector includes the measurement source and reference LED's; an electrical connector for connecting the LED's to the electronics package; optical fibers for transmitting measurement and reflected radiation to and from the optical probe; and optical connector ferrules for connecting reference and reflected radiation to the optical bench. The optical bench comprises a series of mirrors, band pass filters and photomultiplier tube sensors. The optical probe which interfaces with the patient measurement site is connected to the probe connector by an optical fiber bundle comprising a single fiber for each of the measurement radiation LED's and a single fiber for transmitting reflected radiation. To insure accurate control of the measurement radiation LED's and accurate analysis of the transmitted reflected radiation, the electronics package can be customized to work specifically with the probe connector and optical probe. The optical fiber bundle is susceptible to damage from exposure to radiation procedures such as X-ray and CT imaging. To prevent damage to the fiber bundle, the patient interface is typically removed from the patient during radiation procedures.
There remains a need for a spectrometer that is robust to ionizing radiation and provides continuous StO2 monitoring during radiation procedures. To further enhance the usefulness of the spectrometer, any such spectrometer could be compatible with various, generic display units, easy to use, compact, light weight and cost effective to manufacture.